data-fns/src/lib/euclideanSequencer.ts

This library provides utility functions for working with array data that are useful in many contexts, including creative coding. It offers generic functions that perform common operations such as offsetting an array, generating an array based on a callbac

const numSort = (a: number, b: number) => a - b

/**
 * Generates a Euclidean rhythm sequence.
 * @param steps The number of steps in the sequence.
 * @param notes The number of notes in the sequence.
 * @param rotation The rotation of the sequence (default: 0).
 * @returns An array of indices representing the Euclidean rhythm sequence.
 * @example
 * euclideanSequencer(8, 3, 1)
 * // Returns [1, 3, 6]
 */
export const euclideanSequencer = (steps: number, notes: number, rotation = 0): Array<number> => {
  // Check that inputs are positive integers
  if (steps < 0 || notes < 0) {
    throw new Error('Inputs must be positive integers')
  }

  // Initialize an empty sequence array
  const sequence: Array<number> = []

  // Determine the maximum number of notes in the sequence
  const maxNotes = notes > steps ? steps : notes

  // Iterate through the number of notes and calculate the index for each note
  for (let i = 0; i < maxNotes; i++) {
    const index = Math.floor((i * steps) / maxNotes) // Calculate the index using the Euclidean algorithm
    sequence.push((index + rotation) % steps) // Add the index to the sequence, with rotation applied
  }

  // Sort the sequence in ascending order
  return sequence.sort(numSort)
}